Although twin-screw extrusion (TSE) has long been established as one of the most prominent techniques for processing pure polymers as well as polymer composites and nanocomposites, the shear mixing in TSE is often not sufficiently rigorous to exfoliate (separate) and/or disperse (spread) the fillers in composites and nanocomposites. In addition, a long period of exposure to high temperature conditions in TSE can lead to thermal degradation of the materials. These limitations often render TSE ineffective for producing high-performance polymer composites and/or nanocomposites. The solid-state shear pulverization (SSSP) technique has recently been proven as a novel technique to achieve better exfoliation and/or dispersion in polymer composite and/or nanocomposite systems relative to TSE. However, the SSSP technique yields a powder as output or extrudate, which for some intended applications, e.g., those requiring injection molding of the output to shape/mold into a product, is less desirable in terms of ease of handling and safety than the pelletized output from melt extrusion. Furthermore, even when SSSP is followed by melt-extrusion, there would be energy requirements from the two separate instruments, making this two-step process somewhat energy inefficient.
Therefore, a need exists for an extrusion approach that not only achieves good exfoliation and/or dispersion in polymer composites and/or nanocomposites, but also facilitates the production of a non-powder output, thereby eliminating safety concerns and/or problems with powder handling, in a single instrument. In addition, there is a need to develop an approach that is much more energy efficient than the two-step SSSP followed by melt extrusion approach.